S
M
T
W
T
F
S
29
49°
24°
30
44°
21°
1
44°
23°
2
47°
17°
3
45°
24°
4
46°
27°
5
53°
31°
6
53°
25°
7
44°
21°
8
44°
23°
9
45°
17°
10
41°
20°
11
41°
22°
12
50°
23°
13
46°
18°
14
40°
21°
15
44°
22°
16
46°
20°
17
44°
21°
18
48°
27°
19
47°
26°
20
50°
18°
21
41°
19°
22
39°
13°
23
38°
17°
24
39°
16°
25
42°
16°
26
49°
23°
27
40°
15°
28
49°
15°
29
41°
15°
30
Hist. Avg.
46°
21°
31
Hist. Avg.
46°
21°
1
Hist. Avg.
46°
21°
2
Hist. Avg.
46°
21°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
December Weather in Boulder
Boulder's December 2026 forecast shows daily high temperatures ranging from 38° to 53°, with overnight lows between 13° and 31°. The average high for December is 45° with an average low of 21°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how December weather will actually feel in Boulder. See also: January | February | March.
